Looking for dry resist process veondors

Hi,
We have not experienced much success trying to get an uniform resit
coat/exposure process using the conventional methods on our 4 inch
wafers with DRIE etched deep trenches.
We are looking for a vendor who can help us with maybe some 'Riston'
type dry resist coat/expose/develop process.
Thank you for your help.
Sincerly,
John Das, AON